[PATCH v3 1/2] dt-bindings: gpio: add Axiado AX3005 SGPIO controller

[Petar Stepanovic]

Add a Devicetree binding for the SGPIO controller found on the
Axiado AX3005 SoC.

Each SGPIO position provides one fixed-direction input GPIO and one
fixed-direction output GPIO. Input GPIOs support edge-triggered
interrupts.

The controller serializes output values and samples input values over
dedicated data, clock, and latch signals.

Signed-off-by: Petar Stepanovic <pstepanovic at axiado.com>
---
 .../bindings/gpio/axiado,ax3005-sgpio.yaml         | 112 +++++++++++++++++++++
 MAINTAINERS                                        |   8 ++
 2 files changed, 120 insertions(+)

diff --git a/Documentation/devicetree/bindings/gpio/axiado,ax3005-sgpio.yaml b/Documentation/devicetree/bindings/gpio/axiado,ax3005-sgpio.yaml
new file mode 100644
index 000000000000..47ae1285d482
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/axiado,ax3005-sgpio.yaml
@@ -0,0 +1,112 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/axiado,ax3005-sgpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Axiado AX3005 SGPIO Controller
+
+maintainers:
+  - Petar Stepanovic <pstepanovic at axiado.com>
+  - SriNavmani A <srinavmani at axiado.com>
+  - Prasad Bolisetty <pbolisetty at axiado.com>
+
+description: |
+  The Axiado SGPIO controller provides a serial GPIO expansion interface
+  that multiplexes multiple GPIO signals over a small set of physical lines.
+
+  The controller serializes output values on a data output line (DOUT) and
+  samples input values from a data input line (DIN) in synchronization with
+  a shift clock (SCLK). A latch signal (LATCH) updates the output states
+  after each transfer cycle.
+
+  SGPIO positions are organized in banks of 32, with registers controlling
+  output values, input sampling, and interrupt status. The number of SGPIO
+  positions supported depends on the controller configuration.
+
+  The controller detects changes on input GPIOs. Interrupt events are
+  aggregated and signaled through a single interrupt line to the parent
+  interrupt controller.
+
+  Register access is performed over the APB bus. The SGPIO shift clock is
+  derived from the APB clock using a programmable divider.
+
+  Each SGPIO position provides one input and one output, and both are
+  exposed as GPIO lines. Position N is described by two consecutive lines:
+  line 2 * N is the input and line 2 * N + 1 is the output. Directions are
+  fixed by the hardware, so even lines are always inputs and odd lines are
+  always outputs.
+
+  Only input lines can generate interrupts. Rising, falling, and both-edge
+  interrupts are supported.
+
+properties:
+  compatible:
+    const: axiado,ax3005-sgpio
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    description: APB interface clock
+    maxItems: 1
+
+  bus-frequency:
+    description: Desired SGPIO shift clock frequency in Hz
+    minimum: 1
+
+  gpio-controller: true
+
+  '#gpio-cells':
+    const: 2
+
+  interrupt-controller: true
+
+  '#interrupt-cells':
+    const: 2
+
+  interrupts:
+    maxItems: 1
+
+  ngpios:
+    description: |
+      Total number of GPIO lines provided by the controller. Each SGPIO
+      position wired up on the board contributes one input and one output
+      line, so this is twice the number of positions and must be even. It
+      may be lower than the maximum supported by the hardware.
+    minimum: 2
+    maximum: 1024
+    multipleOf: 2
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - bus-frequency
+  - gpio-controller
+  - '#gpio-cells'
+  - interrupts
+  - interrupt-controller
+  - '#interrupt-cells'
+  - ngpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    gpio at 33201c00 {
+        compatible = "axiado,ax3005-sgpio";
+        reg = <0x33201c00 0x400>;
+        clocks = <&apb_clk>;
+        bus-frequency = <1000000>;
+        gpio-controller;
+        #gpio-cells = <2>;
+        interrupt-controller;
+        #interrupt-cells = <2>;
+        interrupt-parent = <&gic500>;
+        interrupts = <GIC_SPI 125 IRQ_TYPE_LEVEL_HIGH>;
+        ngpios = <256>;
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 77159f279621..5bec6ea50c70 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4406,6 +4406,14 @@ S:	Orphan
 F:	Documentation/devicetree/bindings/sound/axentia,*
 F:	sound/soc/atmel/tse850-pcm5142.c
 
+AXIADO SGPIO DRIVER
+M:	Petar Stepanovic <pstepanovic at axiado.com>
+M:	SriNavmani A <srinavmani at axiado.com>
+M:	Prasad Bolisetty <pbolisetty at axiado.com>
+L:	linux-gpio at vger.kernel.org
+S:	Supported
+F:	Documentation/devicetree/bindings/gpio/axiado,ax3005-sgpio.yaml
+
 AXIS ARTPEC ARM64 SoC SUPPORT
 M:	Jesper Nilsson <jesper.nilsson at axis.com>
 M:	Lars Persson <lars.persson at axis.com>

-- 
2.34.1